12. Which of the following statements is correct?
(A) the intemal energy of a system increases when more work is done by the system than heat is flowing into the system
(B) the internal energy of a system decreases when work is done on the system and heat is flowing into the system
(C) the system does work on the surroundings when an ideal gas expands against a constant external pressure
(D) all the statements are true
(E) all the statements are false

8. The sodium salt, NaA, of a weak acid is dissolved in water； no other substance is added. Which of these statements (to a close approximation) is true? (A)(B) (C) (D) (E) none of these

9. Consider two separate solutions of equal concentration. The first solution contains sodium hydroxide, and the second solution contains barum hydroxide. Which solution has the lower pH? (A) the sodium hydroxide solution (B) the barium hydroxide solution (C) the pH's of the two solutions are equal (D) we need to know the concentrations to answer this questio (E) we need to know the volumes to answer this question

10. Identify the strongest basc. (A)(B) CH3OH (C)(D) H2O (E)

11. Which statement is true of a process in which 1 mol of a gas is expanded from state A to state B? (A) when the gas expands from state A to state B, the surroundings are doing work on the system (B) the amount of work done in the process must be the same, regardless of the path (C) it is not possible to have more than one path for a change of state (D) the final volume of the gas will depend on the path taken (E) the amount of heat released in the process will depend on the path taken

13. For the vaporization of a liquid at a given pressure, (A) △G is positive at all temperatures (B) △G is negative at all temperatures (C) △G is positive at low temperatures but negative at high temperatures (and zero at some temperature) (D) △G is negative at low temperatures but positive at high temperatures (and zero at some temperature) (E) none of above

14. is _______ for exothermic reactions and _______ for endothermic reactions. (A) favorablc, unfavorable (B) unfavorable, favorable (C) favorable, favorable (D) unfavorable, unfavorable(E) cannot tell

15. From the following list of observations, choose the one that most clearly supports the conclusion that the mass of the atom is located mainly in the nucleus. (A) the emission spectrum of hydrogen (B) the photoelectric effect (C) the scattering of alpba particles by metal foil (D) diffraction (E) cathode "rays"

16. Which of the following is a reasonable criticism of the Bohr mode] of the atom? (A) it makes no attempt to explain why the negative electron does not eventually fall into the positive nucleus (B) it does not adequately predict the line spectrum of hydrogen (C) it does not adequately predict the ionization energy of the valence electron(s) for elements other than hydrogen (D) it does not adequately predict the ionization energy of the first-energy-level electrons for elements other than hydrogen (E) it shows the electrons to exist outside of the nucleus

17. Which of the following is not determined by the principal quantum number, n, of the electron in a hydrogen atom? (A) the energy of the electron (B) the minin mum wavelength of the light needed to remove the electron from the atorn (C) the size of the corresponding atomic orbital(s) (D) the shape of the corresponding atomic orbital(s) (E) all of the above are determined by n

18. Which of the following statements is false? (A) an orbital can accommodate at most two electrons (B) the electron density at a point is proportional to at that point (C) the spin quantum number of an electron must be either +1/2 or -1/2 (D) a 2p orbital is more penetrating than a 2s； that is, it has a higher clectron density near the nucleus and inside the charge cloud of a Is orbital (E) in the usual order of filling, the 6s orbital is filled before the 4f orbital